Air, high-purity gas, chemical gas and the like may include metals and metallic compound which may exert harmful influences on a human body. In addition, when the atmosphere or a variety of gases included in the metal and the metallic compound are used in a laboratory or a manufacturing site, the experimental result may be failed or the manufactured article may be detected.
In particular, it is generally known in the art that the contamination of an extremely small amount of metal and metallic compound, which are contained in the air of a fabrication environment and process gas, may cause severe failures such as a pattern defect or a circuit short under the environment of for example, a semiconductor fabrication process where cleanliness must be maintained. Accordingly, the states of the fabrication environment and the process gas must be thoroughly managed by rapidly monitoring the extremely small amount of contaminated metal or metal compound. However, there is no device to monitor the metal and the metal compound contained in the air and the process gas in real time or in substantially real time due to problems, such as a technical limitation and an economical aspect in measuring the extremely small amount of metal or metal compound.
According to a conventional technology of measuring metal and metallic compound, since the metal and the metal compound are measured using equipment, such as ICP-MS, or AAS, in a laboratory after sampled by a passive sampler, such as a filter, an impinge, or a wafer, for a long time and being subject to a pre-treatment, significant long time is taken until data are acquired after the sampling. Accordingly, the conventional technology has the limitations when applied to the monitoring of an industrial site or the monitoring of environmental pollution so that the environment may not be improved, or the contamination may not be previously prevented.
Particularly, according to a conventional sampling method, since a significant small amount of metal and metallic compound are contained in the air, a long time of 24 hours to 96 hours is required to sample metal and metallic compounds to the extent of obtaining a meaningful experimental result. In addition, since a complex pre-treatment process must be performed to analyze a sample filter in addition to the trapping process, time and manpower may be significantly wasted. Further, the reliability of data may be degraded as a sample is contaminated through the long-time sampling, the complex pre-treatment process, and the analysis process. Additionally, an analyzer, such as HPIC, or ICP-MS to analyze an extremely amount of a sample is mainly high-priced equipment. Accordingly, actually, after sampling at several points, samples are transferred to one analyzer to be sequentially monitored. In particular, since the fabrication line of a semiconductor or a display is in a large scale, so that the samples must be transferred to the analyzer at the distance of several tens to hundreds of meters, the conventional sampling method may not be easily employed in the field.
The conventional method of measuring the metal and the metallic compound contained in the air has the most fatal disadvantage in that monitoring may not be rapidly performed due to the long-time sampling process. Although the rapid sampling and measuring, that is, the real-time monitoring is significantly required to manage FAB concentration or manage air quality under a general environment, such as yellow dust, in the case of a semiconductor clean room, the real-time monitoring is impossible according to the conventional methods.
Many studies and efforts have been performed to solve the problems. According to a gas diffusion denuder among them, an amount of gas may be increased and the gas may be concentrated. However, since pre-treatment is significantly complex, and sampling is performed for several hours, the variation in the concentration of the gas in a measurement place may not be easily measured, and thus the above problems are not overcome.
Korea Patent Application No. 10-1999-0005926 (entitled “Gas Diffusion Scrubber”, hereinafter, referred to as cited reference 1) discloses a technology of concentrating a solution within a shorter period of time. However, in the case of the cited reference 1, the sampling efficiency is rapidly varied depending on the measurement concentration, and the measurement efficiency is varied depending on the temperature and the humidity, that is, various surrounding conditions. Thus, the metering is significantly difficult. Additionally, since the sampling efficiency is varied depending on the flow rate of gas passing through a diffusion scrubber, the gas must be sampled at a low flow rate. Furthermore, since the efficiency is not uniform depending on conditions, calibration is performed using a gas standard device. Moreover, a gas sample may be additionally contaminated or lost when moving to a long distance. If a sample transfer tube is contaminated, the cleaning of the sample transfer tube may be difficult, so that the tube may be replaced with new one.
Korean Patent Application No. 10-2002-0029197 (entitled “Sampling method of Ammonia Gas with High Efficiency and Monitoring Method of Ammonia Gas”, hereinafter referred to as cited reference 2) discloses an apparatus for not only sampling the ammonia gas at the high efficiency, but monitoring an amount of the ammonia gas in real time by solving the above problem. However, according to the cited reference 2, although gas is sampled only using a normal-temperature absorption solution at a normal temperature, the absorption solution has a low pH, so that the sampling of the acid gas may not be difficult.
Additionally, when a conventional monitoring apparatus for analyzing a sample is applied to a semiconductor or display fabrication line, the scale of the semiconductor or display fabrication line is increased, so that the transfer of the collected sample to an analyzer at a distance of several tens or hundreds of meters may be difficult. Furthermore, a gas sample may be additionally contaminated or lost when moving to a long distance. If a sample transfer tube is contaminated, the cleaning of the sample transfer tube may be difficult, so that the tube may be replaced with new one.